1. Field of the Invention
The present invention relates to a bulb with a glare-protection paint applied thereon and to a vehicular lighting fixture equipped with such a bulb.
2. Prior Art
FIG. 5 shows a conventionally employed glare-protection-paint-applied bulb, and FIG. 6 shows a vehicular lighting fixture provided with a shade that has the glare-protection-paint-applied bulb of FIG. 5.
In this prior art vehicular lighting fixture 100, such as a head lamp, a black glare-protection paint 103 is applied on a top portion 102 (generally referred to as xe2x80x9cblack top coatxe2x80x9d) of a glass tube of the bulb (an H4 halogen bulb or the like) 101, and this bulb 101 is disposed in a light chamber 107 of the lighting fixture 100 which is equipped with a non-stepped transparent front lens 106.
The black glare-protection paint 103 is applied on the top portion 102 of the glass tube so as to cut the light beams emitted forwards from the bulb 101 and prevent the light beams from being directly emitted from the bulb 101 to the outside. In other words, with the black glare-protection paint 103, the light from the bulb 101 is reflected by a reflector 104 (a reflecting mirror encapsulating the bulb 101); and since this reflector 104 is installed so as to tilt by an aiming mechanism, the reflected light can be emitted in a predetermined direction.
However, since the black glare-protection paint 103 applied on the bulb 101 is seen through the transparent front lens 106 and recognized as a macula on the reflector 104 that has a gray color by aluminum evaporation treatment, it is aesthetically inappropriate and causes poor external appearance.
Accordingly, a cone-shaped member called a shade 105 is generally disposed in the light chamber 107. The shade 105 covers and hides the front portion of the bulb 101 or the black glare-protection paint 103, and it also forms the light beams emitted from the bulb 101 into a predetermined light distribution pattern. The shade 105 externally assumes a color of the same group as that of the reflector 104, thus avoiding the black glare-protection paint 103 of the bulb from being recognized as a macula.
However, this conventional light bulb has some technical problems.
(1) Because the reflecting surface of a reflector has been improved greatly in recent years, a predetermined light distribution pattern can be formed only by reflectors. In other words, it is not necessary to use a shade. Nevertheless, in the above prior art, so as to prevent visual recognition of the black glare-protection paint 103 from the outside, the shade 105 is employed to cover the paint 103. The lighting fixture 100 is thus structurally complicated and has an increased overall number of parts. This constitutes a factor of increase of the costs.
(2) The conventionally employed black glare-protection paint 103 of inorganic paint Type contains chrome and lead, and chrome and lead would cause an environmental pollution.
(3) In order to ensure that the black glare-protection paint 103 assumes a gray color that is the same group of color as that of the reflector 104, white titanium dioxide is mixed with the black pigment. However, the problem is that thermal discoloration occurs due to a high temperature.
(4) In addition, so as to prevent degradation of the portion coated with the glare-protection paint that would occur over time, there has been an increased demand for excellent glare-protection performance and an improvement in heat resistance, impact resistance and corrosion resistance.
It is, therefore, an object of the present invention to provide a vehicular bulb that is applied with a glare-protection-paint and to provide a vehicular lighting fixture equipped with such a bulb in which a glare-protection paint of a gray color close to that of the exterior of a reflector is applied on the bulb so that the bulb dispenses with a shade member, has an excellent glare-protection performance, high heat resistance, impact resistance and corrosion resistance and is free from the possibility of causing environmental pollution.
So as to accomplish the object, in the glare-protection-paint-applied bulb according to the present invention, the pigment substance of a glare-protection paint that is applied on part of a glass tube contains silicon carbide (SiC).
In this glare-protection paint, since the silicon carbide that is of a white color group is used, it is ensured that the paint assumes a color that is close or similar to a silver color of a reflector. Thus, without a shade, the bulb is not easily visually recognized from the outside, and it can reduce the number of parts and cut down the costs.
Silicon carbide has a crystal structure in which silicon and carbon are covalently linked at a ratio of 1:1. Thus, silicon carbide has hardness and heat resistance that are higher than those of alumina and silicon nitride. Also, it is high in corrosion resistance. Accordingly, discoloration and damages of the glare-protection paint that would be caused by heat from the bulb can be prevented.
Furthermore, in the glare-protection-paint-applied bulb of the present invention, the color of the glare-protection paint is adjusted so that, the glare-protection paint externally assumes a gray color defined by a range of YN-50 to YN-80 defined in JIS (Japanese Industrial Standard) Standard Color Chart (JIS 8721) by compounding a predetermined amount of black calcined pigment (ceramic black) with the pigment substance of the paint.
In this glare-protection-paint-applied bulb, since a predetermined amount of black calcined pigment is compounded with silicon carbide of a white color group, it is possible to achieve harmonization in the form of protective coloration for a silver color of the aluminum-evaporated surface of the reflector disposed around the bulb.
Furthermore, since it is possible to compensate for relatively low glare-protection performance of silicon carbide by the black calcined pigment, color tone and glare-protection performance can be well balanced.
Furthermore, in the glare-protection-paint-applied bulb of the present invention, an inorganic pigment composed of copper (Cu), iron (Fe) and manganese (Mn) is employed as the black calcined pigment.
With the use of this inorganic pigment, organic pigments which are unendurable and fragile in terms of weathering resistance and heat resistance are not used. Also, chrome, lead and the like, which would cause environmental pollution, are not used in the present invention.
In addition, in the glare-protection-paint-applied bulb according to the present invention, an inorganic pigment composed only of silicon (Si) is also employed as the black calcined pigment.
With the use of inorganic pigment composed only of silicon (Si), all metals are eliminated from the inorganic pigment. Accordingly, the present invention is more environment-friendly.
Furthermore, in the glare-protection-paint-applied bulb according to the present invention, the glare-protection paint contains 20 to 30 weight % of silicon carbide.
With the use of this glare-protection paint that contains 20 to 30 weight % of silicon carbide, the glare-protection paint has a desired gray color with sufficient durability and adhesion properties, regardless of the type of black calcined paint used therein.
Furthermore, the present invention provides a vehicular lighting fixture that is equipped with the glare-protection-paint-applied bulb described above.
In this vehicular lighting fixture, it is difficult to visually recognize the bulb inside the light chamber even though a transparent front lens is used. Therefore, this lighting fixture is aesthetically preferable, demonstrates high durability, and causes no problem of environmental pollution in the process of manufacturing and abandoning.
As seen from the above, the glare-protection-paint-applied bulb and the vehicular lighting fixture equipped with such a bulb according to the invention are technically advantageous in that the external appearance of the vehicular lighting fixture is improved, the costs are reduced since no shade is required, and environment-friendliness is enhanced.